The Open On-Chip Debugger (OpenOCD) aims to provide debugging, in-system
programming and boundary-scan testing for embedded target devices. OpenOCD
uses a "hardware interface dongle" to communicate with the JTAG (IEEE 1149.1)
compliant taps on your target board. OpenOCD currently supports many types
of hardware dongles: USB based, parallel port based, and other standalone boxes
that run OpenOCD internally. It allows MIPS, ARM7, ARM9, XScale and Cortex
based cores to be debugged via the GDB protocol. Flash writing is supported
for external CFI compatible NOR flashes, NAND and several internal flashes.

WWW: http://openocd.sf.net/